Anti-reflective (AR) coatings are generally applied to surfaces of lenses or windows to reduce the reflection of light incident on the surfaces that can cause glare. Typically, the AR coatings are thin films structures that are applied to surfaces using deposition techniques such as sputter deposition, chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD) processes. In some cases, the AR coatings include multiple alternating layers of thin films, which provide materials of different refractive indexes and that improve the anti-reflective qualities of the AR coatings.
In some applications, the surface of a lens or a window has a three-dimensional geometry that makes applying a uniformly thick AR coating difficult. In some applications, CVD processes can offer the ability to conformally coat three-dimensional geometry parts. This is because CVD deposition of thin films occurs due to a chemical reaction at the surface of a part, while some other deposition technologies involve physical or chemical reaction in the gas phase and transport of chemical species to the substrate. However, many films formed using traditional CVD techniques are not adequately dense or durable for certain applications, such as AR coatings for exterior surfaces of consumer products.